1. Field of the Invention
This invention provides a sound system capable of grouping midrange and high frequency drivers together in an enclosure to increase the sound pressure level while minimizing interference problems.
2. Related Art
A sound system in a large spacious area such as an arena, outdoor, or stadium setting requires very high sound pressure levels (SPL) for adequate sound reproduction because of the long distances over which sound waves must travel in order to reach the listener. With the long distance, however, attenuation may develop in the sound waves. This may cause a drop of about 6 dB level of sound amplitude as sound waves travel twice the distances. Attenuation problems in the sound waves may be overcome by producing higher sound pressure levels at the origination of the sound. One way to do this is through grouping a number of loudspeakers together to increase the SPL.
When a group of loudspeakers generate sound there may be an overlapping in the coverage area. Overlapping sound waves, however, interfere with other sound waves. This can cause the overall SPL produced from the group of loudspeakers to be less than the SPL produced from the individual loudspeakers. For example, two sources or drivers generating overlapping patterns may increase the average SPL to about 3 dB over that of one of the two sound sources. By comparison, a coherent summation, where there is little or no interference between two sound sources, would increase the average SPL by about 6 dB over that of one of the two sound sources. Interference may also reduce the intelligibility and coherency of the sound because the sound waves may be arriving at the listener's ears at different times from different sound sources. Another problem may be reverberation within the auditorium due to sound waves bouncing off the walls, affecting the quality of the sound.
In an attempt to minimize the problems of grouping loudspeakers some have tried to incorporate two or three midrange drivers and two or three high frequency drivers into one enclosure. Such an arrangement helps to raise the SPL but there may still be a problem with interference as the drivers do not add up to produce the optimal SPL. Therefore, there still is a need for a sound system that may group midrange and high frequency (HF) drivers to increase the SPL while minimizing interference.